gto1004 issues

Picked up a refurb gto1004 drom harman and have a couple issues.
First, on front channels after setting gain, there is a voltage difference between left and right of about a half volt. Is tha lt normal?

Second, rear amp is reading zero for some reason but its definitely putting out power as my tweets still work (active setup)

Third, due to mids being 2 ohm and tweets at 4 ohm they are set to different voltage but are close in overall value. One is like 17 the other is 20. To reach these though the front channel is at around 9 o'clock and the rear is all the way over to almost maxed out. Shouldn't they be close to around the same setting?